The supplier of the frequency converter braking unit reminds you that the method used for energy consumption braking is to install a braking unit component on the DC side of the frequency converter, which consumes the regenerated electrical energy on the power resistor to achieve braking. This is the most direct way to handle regenerative energy, which is to consume the regenerative energy through a dedicated energy consumption braking circuit on a resistor and convert it into thermal energy. Therefore, it is also known as resistance braking, which includes a braking unit and a braking resistor.
(1) Braking unit. The function of the braking unit is to connect the energy dissipation circuit when the voltage Ud of the DC circuit exceeds the specified limit (such as 660V or 710V), allowing the DC circuit to release energy in the form of thermal energy after passing through the braking resistor. The braking unit can be divided into two types: internal and external. The internal type is suitable for low-power general-purpose frequency converters, while the external type is suitable for high-power frequency converters or working conditions with special requirements for braking. In principle, there is no difference between the two. The braking unit serves as a "switch" to connect the braking resistor, including a power transistor, a voltage sampling comparison circuit, and a driving circuit.
(2) Braking resistor. Braking resistor is a carrier used to consume the regenerative energy of an electric motor in the form of thermal energy, including two important parameters: resistance value and power capacity. Generally, corrugated resistors and aluminum alloy resistors are more commonly used in engineering. Corrugated resistors use surface vertical corrugations to facilitate heat dissipation and reduce parasitic inductance. High flame retardant inorganic coatings are also selected to effectively protect the resistance wires from aging and extend their service life; Aluminum alloy resistors have better weather resistance and vibration resistance than traditional ceramic frame resistors, and are widely used in harsh industrial control environments with high requirements. They are easy to install tightly, easy to attach heat sinks, and have a beautiful appearance.
Le processus de freinage par consommation d'énergie est le suivant : lorsqu'un moteur électrique décélère ou inverse son sens de rotation (y compris lorsqu'il est freiné) sous l'effet d'une force extérieure, il fonctionne en mode générateur et l'énergie est réinjectée dans le circuit CC, ce qui provoque une augmentation de la tension du bus. L'unité de freinage mesure cette tension. Lorsque la tension CC atteint le seuil de conduction défini par l'unité de freinage, le transistor de puissance de cette dernière conduit et un courant circule dans la résistance de freinage. Cette résistance convertit l'énergie électrique en énergie thermique, réduisant ainsi la vitesse du moteur et la tension du bus CC. Lorsque la tension du bus chute en dessous du seuil de coupure défini par l'unité de freinage, le transistor de puissance de cette dernière se bloque et aucun courant ne circule dans la résistance de freinage.